RE: Evaluate complex conditions

SQL can do a lot of work and it is capable of being inefficient.  If it
causes your system to slow way down, then you may have a tuning problem or
the SQLs being executed are pigs.  I can give you some lovely examples of
porcine SQLs - even a few that if coded in RPG would fly.  Such is sometimes
the cost of a tool that doesn't require programming.  I am an AS/400
performance consultant with a moderate amount of experience with both RPG
and SQL.  I like to write MI or C because it is fast and small.  But the
business comes first.  If the customer has decided that SQL is the right
thing for the business to use, then I tune the box the best that I can.  If
that isn't good enough, it is time to evaluate priorities - compare the
business value of using SQL to the cost and complexity of a hardware upgrade
or alternate architecture.

I can do things with a single SQL statement that would take me a day to
write in RPG.  That is a very efficient use of an expensive resources - me.

Richard Jackson
mailto:richardjackson@richardjackson.net
http://www.richardjacksonltd.com
Voice: 1 (303) 808-8058
Fax:   1 (303) 663-4325

-|-----Original Message-----
-|From: owner-midrange-l@midrange.com
-|[mailto:owner-midrange-l@midrange.com]On Behalf Of booth@martinvt.com
-|Sent: Thursday, October 26, 2000 11:30 AM
-|To: MIDRANGE-L@midrange.com
-|Subject: Re: Evaluate complex conditions
-|
-|
-|You suggest that an SQL process is not a performance pig compared to
-|properly written RPGIV program.   Is there any experience out there to
-|support or confute this?
-|
-|I ask because we notice that whenever one of the SQL gurus starts an SQL
-|process off the command line all the rest of us might as well go for
-|coffee until the SQL is done.
-|
-|_______________________
-|Booth Martin
-|Booth@MartinVT.com
-|http://www.MartinVT.com
-|_______________________
-|
-|
-|
-|
-|Marco Facchinetti <facchinetti@yahoo.com>
-|Sent by: owner-midrange-l@midrange.com
-|10/25/2000 05:28 AM
-|Please respond to MIDRANGE-L
-|
-|
-|        To:     MIDRANGE-L@midrange.com
-|        cc:
-|        Subject:        Re: Evaluate complex conditions
-|
-|Martin, if your purpose is a Query Tool my experience says
-|that is better find something ready on the market.
-|About performance: if an sql statement is too heavy the
-|same one done in (eg.) RPG will take a very long time to be
-|executed. If you got the right logical files defined in you
-|DB you'll get good performace if not....
-|Anyway if your are looking to eval or check an expression
-|just remember tha procedure calls can be recursive, so you
-|don't need any stack, procedures do it for you.
-|
-|Enjoy...
-|
-|--- booth@martinvt.com wrote:
-|> I have 4 problems with an SQL solution.
-|>
-|> 1-I don't know SQL well enough to  write the strings on
-|> the fly.
-|> 2-Users I know can't fill in a command line string
-|> suitably for an SQL
-|> solution,
-|> 3-the few instances of SQL selections I've seen have
-|> performance pigs in
-|> that SQL would suck in the sides of the machine in an
-|> interactive job, and
-|> even with that still respond slowly.
-|> 4-giving users full flexibility with and/or selections
-|> just doesn't work
-|> well.  Their intentions are good but the example given
-|> yesterday is a
-|> wonderful example of the problem.  ( "give me all
-|> registered voters in New
-|> Hampshire and Vermont" will list just a few energized
-|> citizens that like
-|> to vote early and vote often.)
-|>
-|> imho
-|> _______________________
-|> Booth Martin
-|> Booth@MartinVT.com
-|> http://www.MartinVT.com
-|> _______________________
-|>
-|>
-|>
-|>
-|> Marco Facchinetti <facchinetti@yahoo.com>
-|> Sent by: owner-midrange-l@midrange.com
-|> 10/24/2000 03:34 AM
-|> Please respond to MIDRANGE-L
-|>
-|>
-|>         To:     MIDRANGE-L@midrange.com
-|>         cc:
-|>         Subject:        Re: Evaluate complex conditions
-|>
-|> SQL?
-|> --- booth@martinvt.com wrote:
-|> > Terry, the only method I've been able to create and
-|> then
-|> > understand again
-|> > a week later, is to make a series of subroutines.  Each
-|> > subroutine will
-|> > have a test for a condition and will flip a flag if the
-|> > condition is not
-|> > met.  Something like this:
-|> >
-|> >  C    Eval      DoItFlag = 'Yes'
-|> >  C    Exsr    Test1
-|> >  C    If         DoItFlag = 'Yes' And Test1Flag = 'Yes'
-|> >  C    EXSR   Test1SR
-|> >  C    End
-|> >  C    If         DoItFlag = 'Yes' And Test2Flag ='Yes'
-|> >  C    EXSR   Test2SR
-|> >  C    End
-|> >  C    If         DoItFlag = 'Yes' And Test3Flag = 'Yes'
-|> >  C    EXSR   Test3SR
-|> >  C    End
-|> >   C    If         DoItFlag = 'Yes'
-|> >  C    EXSR   OKToDoSR
-|> >  C    End
-|> >
-|> >
-|> > _______________________
-|> > Booth Martin
-|> > Booth@MartinVT.com
-|> > http://www.MartinVT.com
-|> > _______________________
-|> >
-|> >
-|> >
-|> >
-|> > Terry Grider <tgrider@arkansas.net>
-|> > Sent by: owner-midrange-l@midrange.com
-|> > 10/23/2000 12:43 PM
-|> > Please respond to MIDRANGE-L
-|> >
-|> >
-|> >         To:     MIDRANGE-L@midrange.com
-|> >         cc:
-|> >         Subject:        Re: Evaluate complex conditions
-|> >
-|> > Sorry guys,  I didn't do a very good job of explaining
-|> > what I was looking
-|> > for.
-|> > I don't mean I want code that is an example of testing
-|> > for complex
-|> > conditions, I
-|> > mean I'm looking for code that will evaluate statements
-|> > like the one in my
-|> > original example and determine the truth of the
-|> > statement.  You see, I'm
-|> > writing
-|> > a query tool and I want the user to be able to provide
-|> > selection criteria
-|> > in an
-|> > english style IF format similar to cobol or other query
-|> > tools I've seen. I
-|> > can
-|> > currently handle simple criteria with "and/or"
-|> > connectors, but I can't
-|> > seem to
-|> > come up with a good method for handling multiple levels
-|> > of parenthesis.
-|> >
-|> > Terry Grider wrote:
-|> >
-|> > > Has anyone ever written or seen an example of program
-|> > code designed to
-|> > > evaluate complex conditions?  For example, if you
-|> > wanted to evaluate a =
-|> > > b and (c = d or c = e or c = f).  I'm looking for
-|> > something that can do
-|> > > multiple levels of parenthesis and all "and/or"
-|> > combinations.
-|> > >
-|> > > --
-|> > > Terry Grider
-|> > > tgrider@arkansas.net
-|
-|
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